feat(api): expand API endpoints for repo, PR, user, workspace management

- Add git operation endpoints: archive, compare branches, diff, tree,
  repository extras
- Add repo endpoints: contributors, delete fork, get branch/commit
  status/deploy key/invitation/member/release/tag/webhook, topics,
  release assets, webhook deliveries/retry
- Add PR endpoints: review requests, templates
- Add user endpoints: block/unblock, follow/unfollow, presence,
  personal access tokens, account restore
- Add workspace endpoints: billing history, approvals, domains,
  integrations, invitations, members, webhooks, restore
- Add internal API, notification API, IM API modules
- Update route configuration and OpenAPI spec

api/pr/labels.rs

@@ -55,7 +55,7 @@ pub struct QP {
     pub offset: Option<i64>,
 }
 
-// ── Repo-level labels ──
+// Section: Repo-level labels
 
 /// List PR labels in a repository
 #[utoipa::path(
@@ -189,7 +189,7 @@ pub async fn delete_label(
     Ok(HttpResponse::Ok().json(ApiResponse::new("Label deleted".to_string())))
 }
 
-// ── PR-level label relations ──
+// Section: PR-level label relations
 
 /// List labels assigned to a PR
 #[utoipa::path(